Per Gul Zarin Kiani, J.(a) Constitution of Pakistan(1973), Article. 42, 49, 260.
—Arts. 42 & 49–Article 42 of the Constitution covers the case of President elect only and the cases of Chairman of Chairman of Senate or Speaker of National Assembly acting as or performing the functions of President in the event of a vacancy in office are beyond its scope–Qualifications for the elected President and his term of office and other related matters are different from those of Chairman of Senate and Speaker of the National Assembly; oaths of office prescribed for them are also dissimilar. [p. 9]A
—Art. 49 & Third Sched.—Imperatives of taking fresh oath of office prescribed for the office of President in the Third Sched. of the Constitution by Chairman of Senate when called upon to act as President in the event of a vacancy caused in the office on account of eventualities visualized by Art. 49 of the Constitution–Constitution of Pakistan does not contemplate a separate fresh oath of office meant for the Pakistan does not contemplate a separate fresh oath of meant for the office of President by the Chairman of Senate or Speaker of National Assembly, on the being called upon to act as or perform the functions of President on account of occurrence of a vacancy in the officer of President; instead, Constitution has already bound them in the prescribed, they will discharge their duties and performs functions of President, they will discharge their duties and perform in the manner indicated in their respective oaths already taken by them–Constitution does not envisage even a momentary vacuum or interregnum in the office of President for a body politic is incomplete without its head–When vacancy in the office of President occurs, Chairman of Senate and in his absence, Speaker of National Assembly takes over to act or perform his functions depending upon the nature of vacancy caused in the office–Such functionaries having already taken oaths upon being inducted in their respective offices, need not take fresh oath when called upon to perform functions of President on account of a vacancy in the office of the President. [p.11]B
—Art. 260–Powers of Acting President–Acting President has all the powers of the elected President whose vacancy he was filling in. [p.12]D